Process of burning fuel



(No Model.) 3 Sheets-Sheet 1. E. B. GOXB.

PROCESS OF BURNING FUEL. No. 499,715. Patented June 20, 1893.

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(No Model.) 8 Sheets-Sheet 2. 1 E. B. (JO-XE; PROCESS OF BURNINGYPUEL.No. 499,715. PatentedJune-20,1893.

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B. B. GOXE. PROCESS OF BURNING FUEL.

No. 499,715. Patented June 20, 1893.

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' UNITED STATES PATENT OFFICE.

ECK LEY B. COXE, OF DRIFTON, PENNSYLVANIA.

PROCESS OF BURNING FUEL.

SPECIFICATION forming part of Letters Patent No. 499,715, dated June 20,1893. Application filed October 6, 1892. Serial No. 448,048- (No model.)

cesses, for the economical burning of coals and other fuels; the objectbeing to provide a process especially adapted for the burning of thesmaller sizes of anthracite coals, including those sizes known in themarket as pea, buckwheat, &c.

In the drawings accompanying and forming a part of this specification,Figure 1 is a sectional side elevation of a furnace suitable forcarrying out my improved process. Fig. 2 is a transverse verticalsection of the furnace, in line cm, Fig. 1. Fig. 3isan enlargeddiagrammatic view similar to a portion of Fig. 1, for furtherillustrating the invention and the manner of practicing the same.

Similar characters designate like parts in all the figures.

According to my present invention, the coal or other fuel to be burnedis first placed in a mass or layer of the proper thickness, and the massor layer ignited; it is then subjected to an air-blast the pressure ofwhich is varied, or gradually reduced, (either continuously orintermittently,) during the combustion period, so that the ignited massis subjected to varying or successivelyreduced pressureblasts during thesuccessive stages of said period. During the stage of thecombustionperiod immediately following the ignition, the fuel,especially if it be coal of the kind specified, is found to properlyrequire a different pressure of blast from that suitable for the laterstages of the combustion. This is due, in my opinion, in part to thechemical changes of the fuel itself during the period of combustion, andalso, in part, to the mechanical change in the mass during said period;both'of which changes should, obviously, be provided'for in order toeffect the burning of the fuel in the most economical manner. Generally,I find the pressure should be reduced as the combustible materialdisappears from the mass; but in some cases, owing to melting andsolidifying of the noncombustible materials,a higher pressure may berequired at the later stage or stages of the combustion-period. V

The improved furnace herein shown and described, for the burning of fuelaccording to my present invention, constitutes the subject-matter of aseparate application, Serial No. 452,202, filed November 16, 1892.

A furnace suitable for practicing my invention may consist, as shown inthe drawings, of the usual inclosing walls at the sides and endsthereof, and, in the absence of a steam-boiler or other device to beheated over the furnace, of the ordinary top-covering. In the drawings,the side-walls are designated in a general way by 2 and 4, respectively,and the furnace-chamber is shown covered by a steam-boiler, B. At theforward end of the furnace-chamber, this is provided with the end-wall3, through which is the passage-way 5, for the supply of fuel to thegrate, said supply being delivered from a suitable hopper or othersource of fuel-supply, as 6. At the rearward end of the furnace-chamber,this is shown provided with a bridge-wall, 7, which is connected with avertical wall, 8, rearward of the traveling grate.

The under side, or floor, of the furnacechamber 0 is formed of the upperrun, 10, of an endless traveling grate, designated in a general *way byG, and preferably composed of a series of similar grate bars, orsections, 9, pivotally connected and carried by the wheels 12 and 14,that are fixed on the two shafts 13 and 15, respectively. The ends ofthe several grate-bars are shown supported by guides, of which those forthe upper run of the grate are designated by 16 and 18, while those forthe lower run 11 are designated by 17 and 19, respectively.

For protection, in practice, of the ends of the grate-bars, and also forprevention of the fine fuel passing over the ends thereof, theside-walls of the furnace are brought over the grate-bar as shown in thesectional view, Fig. 2, the brick-supporting plates, 20 and 22,

of the side-wall extending over the grate-bar by a distance equal to, orgreater than the width of, the end-bar of the grate-section.

Under the upper, or fire-carrying, run, 10,

of the traveling grate is aseries of air-supply chambers, a, b, c and d,which may be two or more in number, four of them being shown in' Figs. 1and 2, and five of them in Fig. 3. In general, I prefer to use not lessthan three such chambers. Each of said chambers is to be suitablysupplied with air, which may be done by blowing the air thereinto bycorresponding pipes, at, l), c and d, shown in end view in Fig. 1. Thedivisional walls between the several air-supply chambers come up closeto the under side-of the upper run of the traveling grate, so as topractically close the chambers the one from the other, with theexception of a slight leakage iusufficient in practice to materiallyaffect the operation of the furnace.

The fuel is fed to each section of the grate at or before the time thisreaches the first air-supply chamber a, and is then carried alongmaintained substantially in Siam quo, over that chamber and thesucceeding chambers b, c and d, during which period the combustiblematerial of the fuel is consumed,the resulting cinder, or ash, beingafterward carried under the bridge-wall 7 and finally delivered over therearward end of the grate into the ash-pit 21. In practice, thecombustion goes on, at one stage or another, throughout nearly theentire length of the furnace, the ignition taking place within a shortdistance of the point where the fuel falls upon the grate, this beingcompletely reduced to cinder over the last chamber, d or e of theseries. The reduction of the fuel by combustion gradually lowers thesame on the grate, (by an amount depending on the nature of the fuel,)so that at the point, 23, where the cinder passes under the bridge-wall,the thickness of the cinder is generally much less than the originalheight of the fuel, as illustrated in Fig. 1. Thefuel being maintainedduring the combustion period,and especially during the later stagesthereof, substantially in statu qua, avoids that mixing of thede-carbonized mineral with the partially burned fuel which occurs by theold methods of replenishing the grate, and which is wasteful in itseifects. The cinder, or ash, 24, over the last chamber, d, of the seriesof air-supply chambers being blown for a short timeafter the combustiblematerial isburned therefrom,is cooled down to a relatively lowtemperature before it passes under the bridge-wall and is dischargedfrom the grate. By this means two economies are eifected: first, the airentering the furnacechamber from said supply-chamber d is heated; andsecond, this heating is effected by the heat of the cinder, which wouldotherwise be lost; this statement applies also to the grate itself,which is thus cooled at the earliest practicable moment and before itreaches the wheels, so that the driving mechanism will be heated to theleast possible degree. Another feature of the organization described isthat the air from the least supply-chamber, after being heated by takingup the heat of the grate and the cinder, is mingled with the partiallyconsumed gases from the more forward portions of the furnace-chamber,and serves to effect the complete combustion of these gases. The cindercarried forward upon the traveling grate, under the wall 7, at therearward end of the grate, as shown at the left-hand in Fig. 1, isdischarged from the grate-sections into a pile, which may be removed,from time to time, by any convenient means, without interrupting theoperation of the furnace.

The particular amount of air-pressure required in the respectiveair-supply chambers will be governed by the kind and mechanicalcondition of the fuel; but the proper relation of the severalair-pressures may be expressed by a formula as follows: Let 00 representthe normal pressure of the air-supply in the chamber d. Then 00-11 willrepresent the airpressure in the second chamber 1), 1 being thedifference between the pressures in the two chambers. The air pressurein the third chamber will be equal to the pressure in the first chamberless a quantity greater than y, and may be represented by :r-(gH-a).Following this method of illustration further, the pressure of theair-supply in the next chamber, d, will be represented by w-(y-|a+b). Inpractice, the quantities y, a and b may sometimes be equal, orsubstantially so; or, these characters may in the formula have differentvalues; so that the pressure in the second chamber may be greater thanin the first.

chamber.

'After the furnace has been put into complete operation, the fireman, byoccasional observation of the burning fuel through observaticn-doors at25 and 26 in the side-wall of the furnace, can, by means of ordinaryairvalves (not shown) to be placed in the airsupply pipes at, b, c andd, readily regulate the pressure in the successive air-chambers so as toproduce the best results and completely reduce the fuel to cinder beforeit reaches the Wall 7. By this means the entire floor of thefurnace-chamber may be kept covered, and the combustible part of thefuel may be consumed with a high degree'of economy.

For a fuller illustration of the principle of the invention, referenceshould now be had to Fig. 3, where the. travel of the fuel is dividedinto the five spaces or divisions, A, B, C, D and E, corresponding tothe five blastchambers a, b, c, d, and e, respectively. The division Aconstitutes the ignition area, the normal line of the ignition itselfbeing represented approximately by the curved line 1 y, shown drawnthrough the fresh coal (orother fuel) at 64, where the mass of fuel isaerated by a moderate blast from the chamber 0,. Becoming ignited at 64,the fuel is carried forward to 54:, over the high-pressure blast fromthe chamber b, and is here raised to a high state of combustion, whichis continued with but little reduction, if any, over the next succeedingchamber, 0. During this period the carbon is reduced by being burned upthroughout the depth of the mass, until it is of too low a percentage tolonger normally maintain the previous high rate of combustion under thehigh-pressure blast from the chambers 11 and 0. Accordingly, pursuant tomy present improvement, the air-blast of chamber dis reduced inpressure, to a point sufficient to normally continue the combustion ofthe fuel in its reduced lowcarbon condition, without chilling the sameby over-blowin g, but still to continue the combustion through nearlythe whole depth of the mass of fuel, and thereby reduce the carbon tothe lowest burning-point thereof, considering both the temperature ofthe mass and the admixture of non-burning mineral with the small residueof carbon. Continuing the process, the hot and slightlyburning cinder at35 is carried along and subj ected to a still lower air-blast from thechamber e, which blast, being relatively small in quantity, is socarbonized by the burning carbon of the lower layers of fuel,below thecinder-line R,as to complete the combustion and leave the mass below thelower ashline, S, without any fire therein. The described operationscontinuing While the mass of fuel is slowly carried along over thesuccessive varying air-blasts, the cinder-line and the ash-linenaturally assume inclined positions in the mass, as indicated in Fig. 3;and during the later stages of the process, this being considered inrespect of any particular portion of the mass of fuel, the combustion iscompleted from the lower side of the mass upward, and the rate ofcombustion is so regulated as to be normal at each successive stage ofthe entire operation.

By means of this process, I am enabled to burn the smallest sizes ofanthracite coals with the highest efficiency, and to do this in apracticable manner, and especially without any re-mixing of theparticles during the later stages of the combustion.

The process of preparing and igniting the fuel, by feeding the same overa heated wall or slope, and delivering the heated fuel overafalling-ledge onto a traveling-grate moving away from said slope, whichprocess, being supplemental and preparatory to that herein claimed andtherefore only partially shown or set forth herein, constitutes thesubjectmatter of a separate application, Serial No. 474,559, filed May17, 1893.

Having thus described my invention, I claim- 1. The herein-describedprocess of burning coal and other fuels, consistingin igniting the massspread in a layer, and subjecting said ignited layer maintainedsubstantially in sta tu quo during the successive stages of thecombustion-period, to successive air-blasts of varying pressure,substantially as described.

2. The herein-described.process of burning coal and other fuels,consisting in igniting the mass spread in a layer, subjecting saidignited layer maintained substantially in statu quo to an air-blast, andreducing the air-blast pressure during the combustion-period,substantially as described.

3. The herein-described process of burning coal and other fuels,consisting in igniting the mass spread in a layer and subjecting theignited layer maintained substantially in stain quo, to successive airblasts of successively reduced pressures during the successive stages ofthe combustion period, substantially as described.

4. The herein-described process for the economical burning of coal andother fuels, consisting in igniting the mass, subjecting the ignitedmass maintained substantially in statu quo to a relatively high pressureair-blast during the earlier part of the combustion-period, subjectingthe burning mass during the later part of the combustion-period to arelatively low pressure air-blast, and mingling said low-pressureair-blast, after this has passed through the nearly consumed fuel, withthe gases from freshly ignited fuel,whereby the partially consumed airof the lowpressure blast is heated and furnishes oxygen for completingthe combustion of said gases, substantially as described.

5. The herein-described process for the economical burning of coal andother fuels, consisting in igniting the fuel and subjecting the same toan air-blast, transferring the ignited fuel maintained substantially instatu quo during the combustion-period to successive areas of reducedair-pressure, supplying the place of the transferred ignited fuel withfresh fuel subjected to ignition and air-blast, and commingling thelow-pressure air-blast passing through the cinder with the products ofcombustion from the freshly ignited fuel, whereby the heat of the cinderis utilized for heating air for supplying the later stages ofcombustion, substantially as described.

6. The process of burning coal and other fuels which consists inigniting the fuel upon a grate subjecting the ignited fuel to anair-blast through the grate, and during the succeeding combustion-periodreducing the pressure of the blast in a ratio corresponding to thereduction of combustible in the fuel, substantially as described.

7. The herein-described method of burning coal and other fuels by acontinuous operation, which consists in spreading andigniting the fuelupon a traveling grate, subjecting the traveling layer of ignited fuelto successive air-blasts of varying pressures at successive points inits course of travel, and supplying fresh fuel at the point of the firstair-blast, to maintain the continuity of the traveling layer,substantially as described and for the purpose specified.

ECKLEY B. OOXE.

Witnesses:

J NO. R. WAGNER, HARRY J. DAVIS.

